Marine speedometers



Jul 2, 1963 w. e. SALO MARINE SPEEDOMETERS Filed Dec. 13, 1960 FIGS FIGI

WILLIAM G. SALO mmg w A TTORNEYS United States Patent MARINE SPEEDOMETERS William G. Salo, 6 Crescent St., Springfield, Vt. Filed Dec. 13, 1960, Ser. No. 75,573 2 Claims. (Cl. 73--181) few moving parts as possible and to provide an arrangement whereby the speedometer may be positioned to be operative while the boat is in the water but clear of a position where it may be damaged when the boat is removed from the water for repairs or trailing. Accordingly, this invention provides an improved marine speedometer which in its operative position during movement of the boat gives accurate readings of velocity and which may be retracted from its operative position to prevent injury due to dragging when the boat is out of the water.

The improved speedometer further provides an arrangement whereby the flow of water into the device is controlled in accordance with the range of speed at which the device is to be operated.

The need for springs required in prior art devices to bias the indicator actuator against water pressure is also eliminated by this invention.

Briefly the invention consists of a generally L-shaped tube, the lower end of which in its operative position is directed towards the bow of the boat. As the boat moves through the water, the liquid enters the submerged end of the tube forcing a piston located therein upwardly. To this piston is attached a calibrated rod extending to the upper end of the tube. As the flow into the tube increases, greater length of the calibrated rod is exposed to the operator who reads directly the speed at which the boat is traveling. Flow into the tube is controlled by the selection of a flow control bushing at the entrance to the tube having an orifice of a selected diameter related to a plurality of vertically arranged apertures through the tube in limiting the flow to that quantity required in producing a measurement of a specific range of speeds encountered. Provisions are incorporated for holding the speedometer in its operative position. When the speedometer is released from this position, a compression spring forces the tube upwardly to raise it above the level of the bottom of the boat thus removing it from a position when it may be damaged by dragging.

These and other objects will become apparent from the following description and the accompanying drawings of a preferred embodiment of the invention wherein:

FIGURE 1 is a side elevation of the device mounted on a boat in its operative position with the boat motionless;

FIGURE 2 is a side elevation of the device in its operative position with the boat in motion;

FIGURE 3 is a side elevation with the speedometer shown partially in section;

FIGURE 4 is a sectional elevation view of a segment of the device showing flow pattern during operation; and

FIGURE 5 is a side elevation of the device mounted on a boat and in its retracted position.

Referring to the drawings, the improved boat speedometer consists of a tube having an upper portion 12 and a lower portion 14 bent at an angle of 90 degrees to the upper portion. This generally L-shaped tube 10 is attached to the rear of the boat by brackets 16 and 18. Between the bracket 16 and a handle clamp 28, rigidly 3,095,738 Patented July 2, 1963 aflixed to the upper portion 12 is a compression spring 30. With the speedometer in its retracted position, shown in FIGURE 5, the upper movement of the tube is limited by a clamp 32 attached to the tube 10 at a position below bracket 18 such that clamp 32 and bracket 18 are in contact at the desired upper limit of movement to clear the bottom of the boat preventing damage to the speedometer when the boat is out of the water. When it is desired to project the tube into its operative position, spring 30 is compressed and the lower tube position 14 is hooked beneath the stern of the boat and aligned by a notched bracket 46 for holding the speedometer in its operative position. By appropriate manipulation of handle clamp 28 which also serves as a direction indicator, the opening of lower portion 12 may be directed towards the bow of the boat. As the boat begins to move, Water enters portion 14 through a flow control bushing 34 provided with an orifice 35 of a selected diameter. The moving fluid within the tube strikes a piston 36 located in the upper portion 12 of the tube. Attached to the piston is a calibrated rod 38 which extends beyond the open end of the upper portion 12 through a bushing 40. Drilled in the upper portion 12 of the tube 10 are a plurality of vertically arranged holes 42 through which the water in the tube escapes. These holes, while shown as being of equal size and spacing, may be of varied shape, size and spacing to function in relationship with the selected orifice 35 to control the water pressure and to provide a linear calibrating scale within the range of speed of operation. -As the speed of the boat increases, the flow through orifice 35 increases resulting in the piston 36 being driven upwardly a greater distance. As a result, the calibrated rod 38 is exposed to a greater extent and may be read directly by the operator. When the boat is motionless, the rod is prevented from sliding completely into the tube 10 by a knob 44 mounted at the top end thereof which is shaped to prevent its passage through bushing 40.

By utilizing pressure control holes 42 in the tube, the need for springs to regulate the movement of the piston 36 carrying the calibrated rod 38 is eliminated.

The calibrations on the rod 38 may be either stamped or painted thereon such that only the Zero mark can be seen when the boat is motionless. As the speed of the boat increases, an increasing number of marked graduations are displayed.

If desired, other catch means well known in the art may be incorporated with the invention to substitute for the described arrangement for holding the speedometer in its operative position. This would allow the device to be mounted on other areas of the boat as well as facilitating projection of the lower portion of the speedometer to depths other than that of the boat bottom.

The applicant has disclosed a preferred embodiment of his invention for the purpose of illustration only to enable one skilled in the art to practice this invention. The illustrative embodiment is therefore not to be limiting as the invention is limited only by the spirit and scope of the appended claims wherein applicant is entitled to a reasonable range of equivalents.

I claim:

1. A speedometer for use with power boats comprising; a generally L-shaped tube having upper and lower portions, a calibrated rod within said upper portion of said tube, a piston mounted at the lower end of said rod for movement therewith within said upper portion, said upper portion provided with a plurality of vertically arranged apertures for controlling the flow of water entering said lower portion and exiting from said upper portion, holding means for maintaining said lower portion in a projected position at a level below that of the boat bottom,

and spring means for retracting said lower portion to a position above the level of the boat bottom on release of said holding means. I

2. A speedometer for use' in measuring relative motion between water and a boat moving thereon comprising; a generally L-shaped tube having upper and lower portions, a calibrated rod within said upper portion of said tube, a piston mounted at the lower end of said rod for movement therewith within said upper portion of said tube, a bushing mounted on the top of said upper portion through which said calibrated rod extends, a flow control bushing mounted on the end of said lower portion of said tube, said flow control bushing provided with an orifice of such a size as to allow the desired flow of fluid within said tube, the upper portion of said tube provided with a pluarity of apertures vertically arranged to allow the exit of fluid flowing within said tube, holding means for maintaining said lower portion in a projected position at a level below that of the boat bottom, spring means for retraction of said lower portion to a level above that of the boat bottom on release of said holding means, and handle means to position the end of said lower portion in the direction of travel.

References Cited in the file of this patent UNITED STATES PATENTS 1,238,498 Dawley Aug. 28, 1917 1,869,962 Golden Aug. 2, 1932 1,869,974 Masters Aug. 2, 1932 1,883,582 Cole Oct. 18, 1932 1,885,933 Masters Nov. 1, 1932 2,576,687 Krehbiel Nov. 27, 1951 2,733,601 Mitchell Feb. 7, 1956 FOREIGN PATENTS 44,910 Sweden May 22, 1917 

1. A SPEEDOMETER FOR USE WITH POWER BOATS COMPRISING; A GENERALLY L-SHAPED TUBE HAVING UPPER AND LOWER PORTIONS, A CALIBRATED ROD WITHIN SAID UPPER PORTION OF SAID TUBE, A PISTON MOUNTED AT THE LOWER END OF THE SAID ROD FOR MOVEMENT THEREWITH WITHIN SAID UPPER PORTION, SAID UPPER PORTION PROVIDED WITH A PLURALITY OF VERTICALLY ARRANGED APERTURES FOR CONTROLLING THE FLOW OF WATER ENTERING SAID LOWER PORTION AND EXITING FROM SAID UPPER PORTION, HOLDING MEANS FOR MAINTAINING SAID LOWER PORTION IN A PROJECTED POSITION AT A LEVEL BELOW THAT OF THE BOAT BOTTOM, AND SPRING MEANS FOR RETRACTING SAID LOWER PORTION TO A POSITION ABOVE THE LEVEL OF THE BOAT BOTTOM ON RELEASE OF SAID HOLDING MEANS. 